There is a need for controllable struts for supporting a load while providing motion control and vibration isolation. There is a need for vehicle cab struts for isolating vibrations and controlling cab motions. There is a need for controllable magnetorheological fluid struts which accurately and economically control and minimize vibrations. There is a need for an economically feasible method of making motion control struts and vehicle suspension systems. There is a need for a robust suspension system and struts for isolating troublesome vibrations and controlling vehicle motions. There is a need for an economic suspension system providing beneficial controlled motion and vibration isolation.